Answer:
Option (c) is correct.
Step-by-step explanation:
Labor (Variable input) hired = 151 units
After hiring this much units of labor, a firm incurred:
Marginal cost of hiring (MFC) = $0.30 and marginal product of labor (MRP) = $0.33
The firm continuing hiring new labor until the point at which marginal cost of hiring labor is equal to the marginal product of labor.
In this case, MFC is less than the MRP, so firm should increase the use of labor till the MFC becomes equal to the MRP.